Controlled tension ribbon cassette

ABSTRACT

An endless ribbon for a wire matrix printer is pulled past the print head as the print head moves along the print line by a feed roll located at the entrance to a cassette which has an elongated gradually-expanding storage chamber which readily permits random folding of the ribbon in the chamber resulting in reduced ribbon tension and more uniform ribbon feed.

United States Patent [1 1 Bonner et a1.

[451 Sept. 11,1973

, Assignee:

CONTROLLED TENSION RIBBON CASSETTE 1 Inventors: Gilbert B. Bonner; Philip A.

. Brumbaugh, both of Endicott, N.Y.

International Business Machines Corporation, Armonk, NY.

Filed: DEC. 20, 1971 2 Appl. No.: 209,684

11s. CI. .L. 226/168, 206/52 R, 226/118, 274/4 R, 274/11 R Field of Search 226/118, 168, 119, 226/196; 352/78; 206/52 R, 52 F; 274/4 R, 4 E, 11 R 1 References Cited UNITED STATES PATENTS 3/1919 Burnett 226/118 Webster 226/118 1,525,939 2/1925 l-lolmes.... 226/118 2,476,705 7/1949 Coutant 352/78 R 3,346,161 10/1967 Ironside 226/196 Primary ExaminerRichard A. Schacher Attorney-Francis V. Giolma et a1,

[57] ABSTRACT An endless ribbon for a wire matrix printer is pulled past the print head as the print head moves along the print line by a feed roll located at the entrance to a cassette which has an elongated gradually-expanding storage chamber which readily permits random folding of the ribbon in the chamber resulting in reduced ribbon tension and more uniform ribbon feed.

6 Claims, 7 Drawing Figures PATENTEDISEPI Hm sum 1 or '3 lNI/E/VTORS GILBERT B. BONNER PHILIP A. BRlUMBAUGH CONTROLLED TENSION RIBBON CASSETTE FIELD OF THE INVENTION The invention relates generally to endless ribbon cassettes and has reference in particular to an endless ribbon cassette for a wire matrix printer.

I nsscnrrrion or THE PRIOR ART Tape cartridges for tape recorders are known in the art wherein an endless tape is fed past recording heads and into a chamber including two distinct sections, as

shown in U. S. Pat. No. 3,464,611, which issued on Sept. 2, 1969, to M. A. Verdone.

SUMMARY OF THE INVENTION Generally stated, it is an object of this invention to provide an improved endless ribbon cassette for a wire matrix printer.

More specifically, it is an object of this invention to provide a simple and effective detachable endless ribbon cassette having improved control of the ribbon tension.

One object of the invention is toprovide for using a single gradually-expanding chamber into which the ribbon is fed directly by a pressure roll in random loops and from whenceit ispulled with a uniform tension past a print head where it is impacted against a document to print. I I

Another object of the invention is to provide for pivotally supporting an endless ribbon cassette with a resilient stop providing a predetermined relation with a rotatable pressure roll for feeding the ribbon.

Yet another object of the lnventionis to provide for operating the pressure roll to feed a ribbon in an endless ribbon cassette in response to movement of the print head during a printing operation.

It is also an important object of the invention to provide for feeding the ribbon in the same direction for opposite directions of movement of the print head.

I Still another object of the invention is to provide for using a nylon print ribbon in a polypropylene percent talc-filled molded plastic cassette that has a single gradually-expanding ribbon chamber to provide uniform ribbon feed attention for a wire matrix printer.

It is also an important object of the invention to provide for using an-elongated curved partition to divide a generally circular endless ribbon storage chamber into a single curved chamber of gradually-expanding width for producing more uniform ribbon feed from said chamber.

Another important object of the invention is to provide for supporting an external loop of ribbon from an endless ribbon cassette with a twist between two supports which are at least five times the ribbon width apart which is far enough apart to maintain the twist between said supports.

In a preferred embodiment of the invention an endless ribbon cassette comprises a generally teardropshapcd ribbon storage chamber having an elongated curved partition dividing it into a single chamber of continuously-expanding width for an endless ribbon having a loop which passes between a print head and a document. The cassette is pivotally mounted adjacent its center and has a projecting lip at the outer edge which is biased by a spring-biased lever to press the ribbon against a feed roll. The feed roll is driven through engagement of a toothed drive wheel with a stationary DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a partial plan view of a wire matrix printer mechanism embodying the invention in one of its forms;

FIGS. 2 and 3 are partial right and left end elevation views, respectively, of the mechanism of FIG. 1 with the cassette removed;

FIG. 4 is a front elevation view of the bottom or base plate of the ribbon cassette of FIGS. 1 and 2;

FIG. 5 is a top plan view of the bottom or base plate of the ribbon cassette;

FIG. 6 is a plan view from the bottom of the cover of the ribbon cassette; and

FIG. 7 is afront view in elevation of the ribboncassette cover showing the relation therewith of the stop lever of FIG. 1.

DESCRIPTION OFA PREFERRED EMBODIMENT Referring to FIGS. 1 through 3, the reference .numeral 10 denotes generally a printer carriage-for movinga Print l-Iead l2 and an EndlessRibbon Cassette 14 for feeding an Endless Ribbon 16 past the print head as it moves along the print line for printing on a Document 18, which is backed by a Plateri 20.

The Printer Carriage 10 comprises a movable Base 22, which is slidably supported on a Shaft 24 by means of Bearings 26 and 28. Themovable Base 22 is moved in either direction along the print line by a threaded Drive Shaft 30, which is rotatable and has Threads 31 which cooperate with threaded Nuts 32 and 34, secured in openings in the Base '22 by means of Clamp Screws 36. The Base 22 is of a stepped construction having an upper Support Surface 38 to which the Print Head 12 is secured and having lower rearwardly Brackets 40 for supporting the Ribbon. Cassette 14.

The Print Head 12 comprises a fan-shaped Support or Base 42 secured to the upper Support Surface 38 by Screws 43 and on which a plurality of magnetic actuators represented by the Actuator 44 are securedfor operating Print Wires 46, which pass through a Guide Member 48 and project from the Tip 49 for impacting the Ribbon 16 against the Document 18 in the manner described in US Pat. No. 3,592.,31 l, which issued on July 13, 1971, to Albert S. Chou and Edgar A. Brown.

The Ribbon 16 is stored in the Cassette 14, which is mounted on the movable Base 22 by means of a Cassette Support 50, securedto the Projections 40 of the base by Screws "51 and having an Arm 52 carrying a Pivot Pin 54 on which the Cassette 14 is pivotally mounted. As shown in FIGS. 4 and 5, the Cassette 14 comprises a relatively flat Base Plate 56 having Notches 57 about. the periphery and having a curved Partition 58 extending from a central Boss 60, which has an Opening 62 for receiving thePivot 54, toward the outer edge of the Base, dividing-the area of the base into adjoining sections. The Base. 56 is generally teardrop-shaped having a generally circular End Portion 64 with the Boss 62 substantially in the center thereof, and

a more or less pointed Projecting Portion 66 adjacent the outer end of the curved Partition 58.

The Bottom or Base Plate 56 of the Cassette 14 is provided with a Cover 70 having a relatively flat Top Portion 71 with a depending peripheral Wall 72, which defines with the curved Partition 58, a single, elongated gradually-expanding passage or chamber for storing the Ribbon 16. A Projection of Rib 69 on the underside of the Top Portion 71 adjacent the Exit opening provides a dam which retards the ribbon exit and helps to restrain multiple folds from exiting. The Wall 72 has one End 73 and in spaced relation therewith an extending flexible Finger Portion 74 which with the outer end of the Partition 58 define Exit and Enhance openings. The Finger 74 carries a U-shaped Clip 76, which provides a guide for the Ribbon 16 entering the cassette. A plurality of Tabs 75 about the Wall 72 cooperate with the Notches 57 of the Base 56 to secure the Cover and Base in operating relation. Base Plate 56 and Cover 70 may be held together by ultrasonic welding, if desired. A projecting Guide Rib 77 adjacent the End 73 provides a guide surface for the Ribbon 16. As shown primarily in FIG. 1, the Cassette 14, when mounted on the Pivot Pin 54, has the flexible Finger Portion 74 located next to a Pressure Roll 78, positioned in the Entrance opening. This roll is rotated to feed the Ribbon 16 into the Cassette 14 through the Entrance opening in a plurality of random loops. The Ribbon 16 exists between the Wall 72 and the Partition 58, where it passes through a Guide Clip 80 projecting in spaced relation with the side Wall 72, past the Print Head 12 in cooperation with Guide Pins 84 and 86, whence it has, as shown, a 180 degree mobeus twist 17 which interchanges the inside and outside surfaces of the ribbon, and passes along the surface of the Cassette Support 50 inside a projectingGuide Pin 88, through the Guide Clip 76 to the Pressure Roll 78, which feeds it back into the Cassette 14.

The Pressure Roll 78 is mounted on a Shaft 90, which is rotatably mounted in the Cassette Support 50 by means of a lower Bearing 91 and has a pair of toothed Drive Wheels 92 and 94 secured thereto adjacent the lower end by means of one-wayClutch Mechanisms 96 and 98 in the hubs thereof, respectively. The toothed Drive Wheels 92 and 94 engage straight sections of toothed Belts 100 and 102, which may be attached to the frame of the printer. The one-way Clutches 96 and 98 are so disposed that the Pressure Roll 78 will be driven in a counterclockwise direction to feed the Ribbon 16 into the Cassette l4 regardless of which direction the Printer Carriage is traveling in. The flexible Finger 74 of the cassette side Wall 72 is maintained in predetermined relation to the Pressure Roll 78 by means of a pivoted Pressure Lever 104, which is pivotally mounted on the Cassette Support 50 and is biased in the direction of the Cassette 14 by means ofa Spring 106. The Lever H04 has a projecting Stop 108, which engages the flexible Finger 74 to bias it against the Pressure Roll 78 for feeding the Ribbon 16. A spring pressure on the order of two pounds has been found suitable. A Locking Tab 110 formed at one end of the Pressure Lever 104 engages an angular Projection 112 from the side Wall 72 to lock the Cassette 14 in the opcrating position. By moving the Pressure Lever 104 on its Pivot 114 the Finger will be released from the Projection 1112 permitting the cassette to be rotated on the Pivot 54 and lifted thereof for replacing the ribbon and cassette.

As the Printer Carriage 10 moves along the print line, the flexible Rack Belts 100 and 102 cause the toothed Drive Wheels 92 and 94 to rotate. Because of the oneway Drive Clutches 96 and 98 the Pressure Roll 12 will always be rotated in a counterclockwise direction, causing the Ribbon 16 to move because of the pressure exerted against the roll by the extending Finger 74 of the side Wall 72 of the cassette. The tension is controlled by means of the Pressure Lever 104, which is biased against the flexible Finger 74 by means of the Spring 106. As the Ribbon 16 moves, it is guided by the throat of the cassette, into an expanding curve, which because of the gradually-expanding width of the chamber allows the ribbon to relax as it moves toward the exit, but still retains its original stuffing pattern. Previous ribbon drives have operated consistently well only with heavy feed roll pressure because of the force required to pull the ribbon out of the cassette. This force was not constant, having peaks of high tension at intervals due to the random ribbon path in the cassette. Where the ribbon was found to have a long internal pull at the exit, the tension increased rapidly. This random pattern was formed by allowing the ribbon to be forced unguided into a container. Heavy feeding pressures are undesirable from the standpoint of tip wear of the Print Wires 46 and increased force necessary to actuate the ribbon drive and move the Carrier 10. It has been found that by controlling the ribbon path in the cassette it is possible to prevent long pulls from forming. The path is controlled by confining the ribbon between two diverging walls so that the space increases as the ribbon is pushed between them. In order to best utilize the space with the longest ribbon possible the Wall 72 is curved so as to provide with the Partition 58 a single, continuous gradually-expanding ribbon chamber in order to effect controlled folding of the ribbon in the cassette. The mobeus twist in the ribbon twists the ribbon degrees and provides for increased fabric life and more even feeding since opposite sides of the ribbon are impacted by the print head 12 on successive passes by the print head. By locating this twist between supports which are at least five times the width of the ribbon apart this twist may be maintained at this location despite continuous movement of the ribbon around its path.

While the invention has been shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

l. A cassette for an endless ribbon comprising a bottom member having an integral partition extending from a central portion toward an edge portion thereof to define a single continuous passage of gradually-expanding width for storing random folds of said ribbon, and

a cover secured to said bottom member having a depending side wall about the edge thereof, defining with said bottom member said passage and provided with openings at the edge ends of said partition to provide both an exit and an entrance for an external loop of said ribbon,

said cassette being generally circularand said bottom portion of said cassette having a central boss at the end of said partition pivotally mounting said cassette at its center on a support which has a pressure roll rotatably mounted on a shaft in said opening, and said side wall having a projecting flexible tongue on one side of said opening defining with said pressure roll the entrance for said ribbon.

2. The invention as defined in claim 1, characterized by a resilient stop carried by said support to engage said tongue and urge it toward said pressure roll.

3. The invention as defined in claim 2, characterized by said partition and said side wall each having a heighth substantially the width of said ribbon, and said cover having a rib projection therefrom to provide a constriction at the ribbon exit.

4. The invention as defined in claim 3, characterized by said support being movable and'said-pressure roll tionary toothed rack member.

5. The invention as defined in claim 4, characterized by the drive for said pressure roll comprising a unidirectional drive havinga pair of toothed drive wheels mounted on the pressure roll shaft by oppositely operating one-way clutch means and engaging stationary toothed rack members on opposite sides thereof to effect unidirectional drive of said pressure roll in response to either direction of motion of said support.

6. The invention as defined in claim 5 characterized by said ribbon having an external loop with a degree twist in it which is maintained between two supports which are at least five times the width of the ribbon apart so that first one side of the ribbon faces the print head when it emerges from said cassette and then the opposite side faces the print head the next time a given portion of said ribbon passes said print head. 

1. A cassette for an endless ribbon comprising a bottom member having an integral partition extending from a central portion toward an edge portion thereof to define a single continuous passage of gradually-expanding width for storing random folds of said ribbon, and a cover secured to said bottom member having a depending side wall about the edge thereof, defining with said bottom member said passage and provided with openings at the edge ends of said partition to provide both an exit and an entrance for an external loop of said ribbon, said cassette being generally circular and said bottom portion of said cassette having a central boss at the end of said partition pivotally mounting said cassette at its center on a support which has a pressure roll rotatably mounted on a shaft in said opening, and said side wall having a projecting flexible tongue on one side of said opening defining with said pressure roll the entrance for said ribbon.
 2. The invention as defined in claim 1, characterized by a resilient stop carried by said support to engage said tongue and urge it toward said pressure roll.
 3. The invention as defined in claim 2, characterized by said partition and said side wall each having a heighth substantially the width of said ribbon, and said cover having a rib projection therefrom to provide a constriction at the ribbon exit.
 4. The invention as defined in claim 3, characterized by said support being movable and said pressure roll being driven by gear means on said shaft engaging a stationary toothed rack member.
 5. The invention as defined in claim 4, characterized by the drive for said pressure roll comprising a unidirectional drive having a pair of toothed drive wheels mounted on the pressure roll shaft by oppositely operating one-way clutch means and engaging stationary toothed rack members on opposite sides thereof to effect unidirectional drive of said pressure roll in response to either direction of motion of said support.
 6. The inventioN as defined in claim 5 characterized by said ribbon having an external loop with a 180 degree twist in it which is maintained between two supports which are at least five times the width of the ribbon apart so that first one side of the ribbon faces the print head when it emerges from said cassette and then the opposite side faces the print head the next time a given portion of said ribbon passes said print head. 